The invention generally relates to gas cooking ranges, and more particularly relates to gas surface ranges that have electrical igniters and a down draft ventilation system.
As is well known, gas surface ranges have been built with down draft ventilation systems. One such example is described in U.S. Pat No. 4,413,610 which issued Nov. 8, 1983. In particular, the range described therein had a cooktop surface with two compartments each of which received a modular plug-in cartridge. One type of cartridge had two surface burners, and the other type included tubular burners in a broiler or grill unit. Each burner of the surface burner cartridge had side jump ports which were adjacent to respective flash tubes that extended horizontally towards a common igniter. When the control knob for either of the two surface burners was turned to the light position, the conductor of the igniter was energized by a high voltage such as 15,000 to 20,000 volts. As a result, an electrical arc jumped from the conductor to a target which was grounded to the frame. Gas from the burner ignition ports which had filled the flash tube was ignited and burned back to the jump ports that carried the flame upwards to light the burner.
The surface range further had a down draft ventilation or exhaust system located in a central region of the cooktop surface between the two compartments that received the plug-in cartridges. The down draft exhaust system included a blower connected to and communicating with a duct having an inlet or mouth defined by an aperture in the cooktop surface. In operation, the blower drew air across the cooktop surface past the cartridges and down into the duct through the aperture. In such manner, cooking effluents such as smoke were drawn from the cooking area. The blower was actuated either by manually turning a control knob, or automatically in response to a grill cartridge being operated.
The American Gas Association requires that surface gas ranges with down draft ventilation systems pass a specified ignition test. In particular, ignition must be attained within four seconds under certain operating conditions. The first condition is that the down draft be set at high speed. The second condition is that the gas pressure be reduced to 3.5 inches water column. The third condition is that a pot be placed on each of the surface burners, presumably thereby increasing the velocity of the air flow in the area of the igniter. Under the AGA test conditions described above, ignition may fail to occur within four seconds if operated with a down draft blower of relatively large capacity such as, for example 400 cubic feet per minute. More specifically, the relatively strong draft at the burner and through the igniter and flash tube region may prevent the proper gas/air mixture for ignition.